Substituent Effects in the 13C-NMR Spectra of Six-Membered Nitrogen Heteroaromatic Compounds

Oszczapowicz, Janusz

doi:10.3390/i6010011

Cited by 8 publications

(4 citation statements)

References 17 publications

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“…The peaks between 140 and 160 ppm in HT-300 and HT-340 are attributed to aromatic carbons adjacent to the oxygen and nitrogen atoms (e.g., C−O and C−N) as well as heteroaromatic derivatives (e.g., pyridine, pyrazine, and pyrimidine). 36,37 The peak at 144.2 ppm in the NMR spectra of both HT-300 and HT-340 revealed carbon adjacent to pyridinic nitrogen. 37 The peaks between 120 and 140 ppm in all of the samples are attributed to the carbon atoms in the benzene derivatives (e.g., C−C and C−H) and other heteroaromatic compounds (e.g., indole and imidazole derivatives).…”

Section: Analysis Of Hydrotreated Biocrudesmentioning

confidence: 99%

“…36,37 The peak at 144.2 ppm in the NMR spectra of both HT-300 and HT-340 revealed carbon adjacent to pyridinic nitrogen. 37 The peaks between 120 and 140 ppm in all of the samples are attributed to the carbon atoms in the benzene derivatives (e.g., C−C and C−H) and other heteroaromatic compounds (e.g., indole and imidazole derivatives). 38,39 The peaks that correspond to olefinic carbons associated with fatty acids and fatty acid amides were also found in the NMR spectra of biocrude, HT-200, HT-250, and HT-300 samples, but they disappeared in the HT-340 spectrum.…”

Section: Analysis Of Hydrotreated Biocrudesmentioning

confidence: 99%

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Understanding the Miscibility and Co-feeding Potential of Hydrothermal Liquefaction Biocrude in Refinery Streams: Role of Hydrodeoxygenation

et al. 2022

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Co-processing of hydrothermal liquefaction biocrudes in existing refineries is attracting tremendous attention for large-scale commercialization of sustainable biofuels. As a result of the higher oxygen content, these biocrudes are not compatible with refinery streams; therefore, co-processing requires an essential (stand-alone) prior mild hydrotreating step. Therefore, Spirulina biocrude and mild hydrotreated samples (200, 250, 300, and 340 °C) were comprehensively investigated for their compatibility and solubility behavior with straight-run gas oil (SRGO) and rapeseed oil (RO). In total, 245 solubility tests were performed in 35 different solvents, and these tests provide the basis for theoretical predictions made by Hansen solubility parameters (HSPs) and three-dimensional Hansen double-sphere solubility plots. The compatibility of biocrude samples with SRGO and RO was verified by the overlapping area in their Hansen double-sphere plots and center-to-center distances (D cc). All of these values were found to be in direct relation with the degree of hydrodeoxygenation (HDO), meaning that higher compatibility is strongly dependent upon higher oxygen removal. Experimental miscibility studies confirmed the theoretical predictions and exhibited that severe HDO (93.4%) is needed to achieve the complete miscibility of the biocrude sample (mildly hydrotreated at 340 °C) in SRGO and RO. 13C nuclear magnetic resonance spectroscopy was used to effectively study the functional groups, and the obtained spectra corroborated with the results obtained from theoretical and experimental studies. The finding that HSPs can predict compatibilities of complex biocrudes very close to experimental results and a severe HDO (>90%) is essential to enhance solubility will pave a way in assessing the co-processing scenario.

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Section: Analysis Of Hydrotreated Biocrudesmentioning

confidence: 99%

Section: Analysis Of Hydrotreated Biocrudesmentioning

confidence: 99%

Understanding the Miscibility and Co-feeding Potential of Hydrothermal Liquefaction Biocrude in Refinery Streams: Role of Hydrodeoxygenation

et al. 2022

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“…Thus, the 13 C NMR spectra of the decomposition products are identical to those of the "free", i.e., uncoordinated, dpkoxH compound. The spectra exhibit the 11 signals expected for the carbon atoms of the organic molecule in the δ 121.7-155.9 ppm region [36,[41][42][43][44]. The signal at δ 155.2 ppm is due to the carbon atom of the oxime group [36]; exact assignments of the pyridyl 13 C resonances would be risky.…”

Section: Spectroscopic Characterization In Briefmentioning

confidence: 99%

Reactions of Cadmium(II) Halides and Di-2-Pyridyl Ketone Oxime: One-Dimensional Coordination Polymers

Stamou,

Dechambenoit,

Lada

et al. 2024

Molecules

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The coordination chemistry of 2-pyridyl ketoximes continues to attract the interest of many inorganic chemistry groups around the world for a variety of reasons. Cadmium(II) complexes of such ligands have provided models of solvent extraction of this toxic metal ion from aqueous environments using 2-pyridyl ketoxime extractants. Di-2-pyridyl ketone oxime (dpkoxH) is a unique member of this family of ligands because its substituent on the oxime carbon bears another potential donor site, i.e., a second 2-pyridyl group. The goal of this study was to investigate the reactions of cadmium(II) halides and dpkoxH in order to assess the structural role (if any) of the halogeno ligand and compare the products with their zinc(II) analogs. The synthetic studies provided access to complexes {[CdCl2(dpkoxH)∙2H2O]}n (1∙2H2O), {[CdBr2(dpkoxH)]}n (2) and {[CdI2(dpkoxH)]}n (3) in 50–60% yields. The structures of the complexes were determined by single-crystal X-ray crystallography. The compounds consist of structurally similar 1D zigzag chains, but only 2 and 3 are strictly isomorphous. Neighboring CdII atoms are alternately doubly bridged by halogeno and dpkoxH ligands, the latter adopting the η1:η1:η1:μ (or 2.0111 using Harris notation) coordination mode. A terminal halogeno group completes distorted octahedral coordination at each metal ion, and the coordination sphere of the CdII atoms is {CdII(η1 − X)(μ − X)2(Npyridyl)2(Noxime)} (X = Cl, Br, I). The trans-donor–atom pairs in 1∙2H2O are Clterminal/Noxime and two Clbridging/Npyridyl; on the contrary, these donor–atom pairs are Xterminal/Npyridyl, Xbridging/Noxime, and Xbridging/Npyridyl (X = Br, I). There are intrachain H-bonding interactions in the structures. The packing of the chains in 1∙2H2O is achieved via π-π stacking interactions, while the 3D architecture of the isomorphous 2 and 3 is built via C-H∙∙∙Cg (Cg is the centroid of one pyridyl ring) and π-π overlaps. The molecular structures of 1∙2H2O and 2 are different compared with their [ZnX2(dpkoxH)] (X = Cl, Br) analogs. The polymeric compounds were characterized by IR and Raman spectroscopies in the solid state, and the data were interpreted in terms of the known molecular structures. The solid-state structures of the complexes are not retained in DMSO, as proven via NMR (1H, 13C, and 113Cd NMR) spectroscopy and molar conductivity data. The complexes completely release the coordinated dpkoxH molecule, and the dominant species in solution seem to be [Cd(DMSO)6]2+ in the case of the chloro and bromo complexes and [CdI2(DMSO)4].

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“…c Experimental value for benzene is in the [brackets] from Ref. [45]. Investigating properties of matters at the atomic scales is an advantage of computational chemistry studies revealing insightful information about the structural characteristics of matters.…”

Section: Structural Optimizationsmentioning

confidence: 99%

Chemically uracil–functionalized carbon and silicon carbide nanotubes: Computational studies

Harismah

Mirzaei

Sahebi

et al. 2018

Materials Chemistry and Physics

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Substituent Effects in the 13C-NMR Spectra of Six-Membered Nitrogen Heteroaromatic Compounds

Cited by 8 publications

References 17 publications

Understanding the Miscibility and Co-feeding Potential of Hydrothermal Liquefaction Biocrude in Refinery Streams: Role of Hydrodeoxygenation

Understanding the Miscibility and Co-feeding Potential of Hydrothermal Liquefaction Biocrude in Refinery Streams: Role of Hydrodeoxygenation

Reactions of Cadmium(II) Halides and Di-2-Pyridyl Ketone Oxime: One-Dimensional Coordination Polymers

Chemically uracil–functionalized carbon and silicon carbide nanotubes: Computational studies

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